Semiconductor device and process for producing the same

ABSTRACT

An intermetal insulating film containing at least silicon atoms, oxygen atoms and carbon atoms with the number ratio of oxygen atom to silicon atom being 1.5 or more and the number ratio of carbon atom to silicon atom being 1 to 2, and having a film thickness shrinkage at a time of oxidation of 14% or less is very low in dielectric constant, high in selectivity against resist etching and can be used without using a silicon oxide protective film in a semiconductor device.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a semiconductor device and a processfor producing the same. More particularly, the present invention relatesto a semiconductor device suitable for high speed operation with lowconsuming electric power and a process for producing the same.

[0002] With miniaturization of semiconductor devices, parasiticcapacitance of multilevel wiring becomes the same level as parasiticcapacitance of transistor per se, and operational speed of LSI devicesstrongly depends on the wiring capacitance. Thus, introduction ofinsulating films having a relative dielectric constant (k) lower thanthat of a conventional silicon oxide film (k˜4) (hereinafter referred toas “a low dielectric constant film”) has been studied extensively.

[0003] FIGS. 1 to 4 are cross-sectional views explaining how to use aconventional low dielectric constant film. These drawings show a step offorming inlaid wires by a damascene process as an example. First, asilicon oxide film 9 as a protective film is formed on a low dielectricconstant film 8 in about 100 nm thick or more to form a layered film, onwhich a trench pattern 16 is formed (FIG. 1). After removing the resist6 (FIG. 2), a thin film of titanium nitride, tantalum nitride, or thelike is formed as a barrier metal, followed by formation of copper 18(FIG. 3). Then, the copper and the barrier metal are removed bychemical-mechanical polishing (CMP) method, while retaining the copperand the barrier metal only in the trench pattern to formelectroconductive portions such as wires and vias (FIG. 4).

[0004] As the material for the low dielectric constant film 8, thefollowing three materials, that is, fluorinated siloxane type insulatingfilms (k˜3.5), organic polymer type insulating films (k˜3), and organicsiloxane type insulating films (k˜3) have been mainly studied.

[0005] Among them, the fluorinated siloxane type insulating films are afilm having Si—O—Si networks terminated by Si—F bonds (see Proceedingsof VLSI Multilevel Interconnection Conference 1997, p. 119-124). Thefluorine in the film reacts with a barrier metal 17 such as titaniumnitride, tantalum nitride, etc. In order to prevent delamination,silicon oxide protective film 9 is used.

[0006] The organic polymer type insulating films include a film havingnetworks made of carbon. As the polymer, benzocyclobutene type, aromaticresins, and the like are mainly studied. Since both the organic polymerfilm and the resist 6 are organic films, etching selectivity of thepolymer to the resist is low. Thus, in order to obtain practical patternprocessing conditions good in shape controlling properties, a siliconoxide protective film 9 is used as a hard mask (see Proceedings ofInternational Interconnect Technology Conference 1999, p. 59-61).

[0007] The organic siloxane type insulating films are a film havingSi—O—Si networks terminated by Si—R bonds (R is an organic group). Asthe R, it is general to use a methyl group excellent in heat resistance.As another component, it is possible to include Si—H bonds. The organicsiloxane type insulating films have weak adhesiveness to a metal such astitanium nitride, tantalum nitride, etc. Thus, in order to preventdelamination of the metal during CMP, it is desirable to use as anadhesion layer a silicon oxide protective film 9 (see SemiconductorInternational November 1999, p. 56-64).

[0008] As a process for forming the organic siloxane type insulatingfilm, there have been studied a process of spin coating an alcoholsolution of methylalkoxy-silane oligomer (an organic spin-on glassliquid), followed by baking, and other various chemical vapor deposition(CVD) processes.

[0009] A typical example of forming an organic siloxane insulating filmby CVD process is conducted by using an organic silane and an oxidizinggas. For example, there are disclosed a plasma CVD process usingR_(n)SiH_(4−n) and an oxidizing gas (Proceedings of InternationalSociety for Optical Engineering (SPIE), vol. 3881, p. 8-14, 1999), and aplasma CVD process using (CH₃)₃SiH, N₂O and He (Electrochemical SocietyProceedings vol. 98-6, p. 145-152, 1998).

[0010] Another plasma CVD process using (CH₃)₂Si(OCH₃)₂ and an inert gasis disclosed in the 60th Japan Society of Applied Physics ScientificLectures, Preprint lp-ZN-9, 1999.9 held at Konan University. Accordingto this report, the gas flow rate is reduced to about {fraction (1/10)}of usual flow rate in order to prolong the residence time of the gasesin a reactor. The results of this report are reflected in JP-A11-288931.

[0011] The above-mentioned low dielectric constant intermetal insulatingfilms require a silicon oxide film as a protective film on an uppersurface. Considering a practical process margin, the film thickness isrequired to be about 100 nm at the minimum. This thickness is about ⅓ ofthe wire thickness of fine wiring (e.g. about 300 nm in 0.18 μm-nodeCMOS devices). Thus, an effective dielectric constant between adjacentwires is greatly influenced by the dielectric constant of silicon oxideprotective film (k˜4) to make the dielectric constant higher than thatof the low dielectric constant film per se.

[0012] Among the low dielectric constant films mentioned above, the useof a protective film is inevitable in the case of the fluorinatedsiloxane type insulating films and the organic polymer type insulatingfilms. When the amount of fluorine in the fluorinated siloxane typeinsulating films is reduced, the low dielectric constant properties ofthe film are lost. In the case of the organic polymer type insulatingfilms, the etching selectivity against resist etching cannot be enhancedessentially.

[0013] In contrast, in the case of the organic siloxane type insulatingfilms, a component such as fluorine which reacts with the metal is notincluded. Furthermore, the selectivity against resist etching can beenhanced. Therefore, if the problem of delamination is solved, it ispossible to use the organic siloxane type insulating films without usinga silicon oxide protective film.

[0014] But, when the carbon in the film is remarkably large as in thecase of the film formed by plasma CVD process using (CH₃)₃SiH, N₂O, andHe mentioned above, it is impossible to enhance the selective ratioagainst resist etching. When the carbon content is reduced, adhesivenessis clearly improved, but the dielectric constant is also increased.

SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to provide asemiconductor device using as an intermetal insulating film an organicsiloxane type insulating film having a low dielectric constant, and ahigh selectivity against resist etching and causing no problem ofdelamination without using a silicon oxide protective film, and aprocess for producing the same.

[0016] The present invention provides a semiconductor device includingone or more intermetal insulating films, each intermetal insulating filmcontaining at least silicon atoms, oxygen atoms, and carbon atoms withthe number ratio of oxygen atom to silicon atom being 1.5 or more andthe number ratio of carbon atom to silicon atom being 1 to 2, and havinga shrinkage in the film thickness direction at a time of oxidation of14% or less.

[0017] The present invention also provides a process for producing asemiconductor device comprising

[0018] a step of forming an intermetal insulating film using a mixed gascomprising

[0019] (i) a vapor of monomethyltriethoxysilane represented by theformula: RSi(OR′)₃, wherein R is a methyl group and R′ is an ethylgroup, and a non-oxidizing gas

[0020] (ii) a vapor of methylethoxysilane represented by the formula:R_(n)Si(OR′)_(4−n), wherein R is a methyl group, R′ is an ethyl group,and n is 0 to 2, said vapor being mixed so as to make R 0.75 to 1.5 persilicon, and a non-oxidizing gas, or

[0021] (iii) (a) a vapor of monomethyltriethoxy-silane represented bythe formula: RSi(OR′)₃, wherein R and R′ are each methyl group, or (b) avapor of methylmethoxysilane represented by the formula:R_(n)Si(OR′)_(4−n), wherein R and R′ are each methyl group, and n is 0to 2, said vapor being mixed so as to make R 0.75 to 1.5 per silicon,and a non-oxidizing gas, by means of a plasma chemical vapor depositionmethod, and

[0022] a step of forming wires.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIGS. 1 to 4 are cross-sectional views explaining a prior artprocess for producing a semiconductor device using a low dielectricconstant intermetal insulating film.

[0024]FIGS. 5 and 6 are cross-sectional views explaining problems inprior art organic siloxane intermetal insulating films.

[0025]FIG. 7 is a rough sketch explaining a volume change of Si—CH₃ byoxidation.

[0026]FIG. 8 is a rough sketch explaining a volume change of Si—C—Si byoxidation.

[0027]FIG. 9 is a diagrammatic view illustrating the plasma CVDapparatus used in Example 1 of the present invention.

[0028]FIG. 10 shows FTIR spectrum obtained in Example 1 of the presentinvention.

[0029]FIG. 11 is a graph showing pressure dependency of FTIR spectraobtained in Example 2 of the present invention.

[0030]FIG. 12 is a graph showing pressure dependency of the filmthickness shrinkage obtained in Example 2 of the present invention.

[0031]FIG. 13 is a graph showing the n dependency of dielectricconstants and the number ratio of atoms obtained in Example 3 of thepresent invention.

[0032] FIGS. 14 to 23 are cross-sectional views explaining the processof Example 4 of the present invention.

[0033] FIGS. 24 to 30 are cross-sectional views explaining the processof Example 5 of the present invention.

[0034] FIGS. 31 to 35 are cross-sectional views explaining the processof Example 6 of the present invention.

[0035] FIGS. 36 to 41 are cross-sectional views explaining the processof Example 7 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0036] The present inventors have found that disadvantages produced byusing the prior art organic siloxane insulating films can be solved byusing an organic siloxane insulating film having a small volume change(shrinkage particularly in the film thickness direction) at the time ofoxidation, and accomplished the present invention.

[0037] For example, according to JP-A 11-288931, since a siliconhydrocarbon compound, e.g. a compound having at least one Si—O bond, twoor less O—C_(n)H_(2n+1) bonds, and at least two hydrocarbon groups suchas methyl groups being bound to Si, is used as a reaction gas, theresulting insulating film is poor in adhesiveness to a metal such astitanium nitride, tantalum nitride, etc. Further, since no Si—C—Si bondis formed, it is impossible to expect prevention of shrinkage caused byoxidation.

[0038] When a metal layer is formed on the conventional organic siloxaneinsulating film without a protective layer, only the metal layer isdelaminated from the surface of the insulating film. This is because theorganic component (methyl group) in the insulating film inhibit theadhesiveness.

[0039] But in a practical process, the mechanism of delamination isdifferent to some extent. On the surface of the organic siloxaneinsulating film 8 a forming the trench pattern, a thin oxide layer 8 bis produced (FIG. 5). This is because the surface is oxidized by anoxygen plasma treatment for removing a resist. The film thickness of theoxide layer depends mainly on the pressure of oxygen plasma treatment.When the pressure is 50 mTorr or less, the film thickness can be madeabout 10 nm or less. The adhesiveness between the oxide layer and ametal such as titanium nitride, tantalum nitride, etc. is sufficientlystrong. But, when there is mechanical strain between the oxide layer 8 band the non-oxidized organic siloxane insulating film 8 a under theoxide layer, a portion of the interface is delaminated during thechemical-mechanical polishing (FIG. 6). The larger the shrinkage at thetime of oxidation, the greater the mechanical strain.

[0040] In a practical process, only the surface is oxidized so as not tooxidize the inside of film. In such a case, it is difficult to measurethe shrinkage precisely. Therefore, in the present invention, theshrinkage is measured by intentionally oxidizing the inside of the filmusing a high-pressure plasma treatment, which is not used in thepractical process. The resulting shrinkage is used for the definition inthe present invention for convenience. Film materials having a smallershrinkage according to the above definition, show smaller shrinkage andsmaller mechanical strain when only the surface is oxidized, resultingin giving almost no delamination fundamentally. In order to sufficientlyoxidize the inside of the film, the oxygen plasma treatment can beconducted under a high pressure of 1 Torr or more. A suitable filmthickness for the measurement is preferably about 100 to 300 nm. Whenthe thickness is too small, the measurement becomes inaccurate, whilewhen the thickness is too large, oxidation into the inside of the filmbecomes difficult.

[0041] When the conventional organic siloxane insulating film (k˜3) isoxidized by this way, the shrinkage becomes 20% or more as shown in FIG.12. This is because separated Si atoms by Si—CH₃ bond are combined toform a siloxane bond (Si—O—Si) (FIG. 7). When Si—H bond is contained inthe film, this bond also contributes to the shrinkage of the film.

[0042] As the organic component which does not bring about shrinkage dueto oxidation, there is a Si—C—Si bond. When this bond is replaced by thesiloxane bond by oxidation, the volume is not changed largely (FIG. 8),rather, slightly increases. Thus, by replacing a part of the Si—CH₃ bondby the Si—C—Si bond, the shrinkage of the insulating film at the time ofoxidation can be controlled 14% or less, preferably 10% or less withoutcausing the problem of delamination of the organic siloxane insulatingfilm.

[0043] This is a novel inventive idea not taught by JP-A 11-288931wherein a large amount of Si—CH₃ bonds are used and there is noinventive idea of replacing a part of the Si—CH₃ bond by the Si—C—Sibond.

[0044] According to the present invention, there is provided asemiconductor device including one or more intermetal insulating films,each intermetal insulating film containing at least silicon atoms,oxygen atoms, and carbon atoms with the number ratio of oxygen atom tosilicon atom being 1.5 or more and the number ratio of carbon atom tosilicon atom being 1 to 2, and having a shrinkage in the film thicknessdirection at a time of oxidation of 14% or less.

[0045] It is preferable to make the shrinkage in the film thicknessdirection at a time of oxidation 10% or less.

[0046] The number ratio of oxygen atom to silicon atom is preferably 1.5or more and the number ratio of carbon atom to silicon atom ispreferably 1 to 2. When the number of carbon atoms is small, it isimpossible to make the intermetal insulating film have low dielectricconstant (k<3.5). when the number of oxygen atoms is too small or thenumber of carbon atoms is too large, it is impossible to enhance theselective ratio against resist etching.

[0047] The intermetal insulating film preferably has all of Si—CH₃ bond,Si—O—Si bond and Si—C—Si bond.

[0048] The semiconductor device of the present invention can be producedby a process comprising:

[0049] a step of forming an intermetal insulating film using a mixed gascomprising

[0050] (i) a vapor of monomethyltriethoxysilane represented by theformula: RSi(OR′)₃, wherein R is a methyl group and R′ is an ethylgroup, and a non-oxidizing gas

[0051] (ii) a vapor of methylethoxysilane represented by the formula:R_(n)Si(OR′)_(4−n), wherein R is a methyl group, R′ is an ethyl group,and n is 0 to 2, said vapor being mixed so as to make R 0.75 to 1.5 persilicon, and a non-oxidizing gas, or

[0052] (iii) (a) a vapor of monomethyltriethoxy-silane represented bythe formula: RSi(OR′)₃, wherein R and R′ are each methyl group, or (b) avapor of methylmethoxysilane represented by the formula:R_(n)Si(OR′)_(4−n), wherein R and R′ are each methyl group, and n is 0to 2, said vapor being mixed so as to make R 0.75 to 1.5 per silicon,and a non-oxidizing gas, by means of a plasma chemical vapor depositionmethod, and

[0053] a step of forming wires.

[0054] These steps can be repeated a plurality of times to obtain thepredetermined numbers of the intermetal insulating films and the wiringlayers.

[0055] In the above-mentioned process, individual Si—OR′ bonds combineto form Si—O—Si bonds, while partly decomposed Si—CH₃ bonds combine toform Si—C—Si bonds.

[0056] In the above process, the non-oxidizing gas should be used. Whenan oxidizing gas is used, the Si—CH₃ bonds and Si—C—Si bonds necessaryfor the intermetal insulating film are decomposed. It is preferable toremove unnecessary organic component (R′) not contributing to thebinding of the film from the resulting film as large as possible.

[0057] As the non-oxidizing gas, it is preferable to use a gascontaining a reducing component such as nitrogen, hydrogen, ammonia or amixture thereof, and to remove the organic components in the form ofHCN, comparing with a simple use of an inert gas such as He, Ar, etc.When hydrogen or ammonia is used, it is necessary to use an apparatusfor removing such a gas from the viewpoint of safety, resulting inmaking the apparatus complicated. Considering this, the use of a mixtureof a nitrogen gas and an inert gas such as He, Ar, etc. is morepreferable.

[0058] Further, in order to reduce the unnecessary organic componentsfrom the resulting film, it is preferable to heat a substrate such as asemiconductor substrate at 350 to 400° C. during the film formation.

[0059] In order to form the Si—C—Si bonds by the above-mentioned CVDprocess, it is preferable to make the residence time of the reaction gasin the reactor (or reaction chamber) shorter. When the residence time islong, carbon components in the reaction products in the atmosphere ofthe reactor become larger. As a result, the decomposition reaction ofSi—CH₃ is suppressed, and production of Si—C—Si is reduced. In addition,the amount of unnecessary organic components (R′) not contributing tothe binding of the film increases.

[0060] As an amount proportional to the residence time, there is afactor of (pressure in the reactor)·(volume of the reactor)/(total gasflow rate) [in FIG. 11, this factor is simply expressed by“PRESSURE·VOLUME/TOTAL FLOW RATE”]. In order to form the Si—C—Si bondand to suppress the shrinkage of the resulting film, it is preferable tomake this factor 500 Torr.sec or less, more preferably 280 Torr.sec orless.

[0061] In order to make the amount of carbon and oxygen in the resultinginsulating film suitable, it is preferable to make R in themethylalkoxysilane 0.75 to 1.5 per silicon when R′ is a methyl group,and 0.75 to 1.5 per silicon when R′ is an ethyl group, while n is 0 to 2in the formula: R_(n)Si(OR′)_(4−n). So long as satisfying the aboveconditions, it is possible to use a single vapor (e.g. n=1) or a mixedvapor of alkoxysilanes (n=0-2). From the viewpoint of simplicity of theapparatus, it is preferable to use a single vapor. In addition, there isno difference whether R′ is a methyl group or an ethyl group, butconsidering the vapor pressure and easiness for handling, the casewherein R′ is an ethyl group is more preferable.

[0062] The semiconductor device of the present invention includesfurther the following embodiments.

[0063] (1) A semiconductor device including one or more wiring layers,each layer having a plurality of inlaid wires and intermetal insulatingfilms between individual trench wires, said intermetal insulating filmbeing a single layer film of a low dielectric constant film having adielectric constant lower than that of a silicon oxide film.

[0064] (2) A semiconductor device mentioned in above (1), wherein thelow dielectric constant film contains at least silicon atoms, oxygenatoms and carbon atoms with the number ratio of oxygen atom to siliconatom being 1.5 or more and the number ratio of carbon atom to siliconatom being 1 to 2, and has a shrinkage in the film thickness directionat a time of oxidation of 14% or less.

[0065] (3) A semiconductor device mentioned in above (1), wherein thelow dielectric constant film contains at least silicon atoms, oxygenatoms and carbon atoms with the number ratio of oxygen atom to siliconatom being 1.5 or more and the number ratio of carbon atom to siliconatom being 1 to 2, and has a shrinkage in the film thickness directionat a time of oxidation of 10% or less.

[0066] (4) A semiconductor device including one or more wiring layers,each layer having a plurality of inlaid wires and intermetal insulatingfilms between individual trench wires, said intermetal insulating filmbeing a stack of a plurality of insulating films, the uppermostinsulating film being a low dielectric constant film having a dielectricconstant lower than that of a silicon oxide film.

[0067] (5) A semiconductor device mentioned in above (4), wherein thelow dielectric constant film contains at least silicon atoms, oxygenatoms and carbon atoms with the number ratio of oxygen atom to siliconatom being 1.5 or more and the number ratio of carbon atom to siliconatom being 1 to 2, and has a shrinkage in the film thickness directionat a time of oxidation of 14% or less.

[0068] (6) A semiconductor device mentioned in above (4), wherein thelow dielectric constant film contains at least silicon atoms, oxygenatoms and carbon atoms with the number ratio of oxygen atom to siliconatom being 1.5 or more and the number ratio of carbon atom to siliconatom being 1 to 2, and has a shrinkage in the film thickness directionat a time of oxidation of 10% or less.

[0069] Further, the process for producing a semiconductor device of thepresent invention includes the following embodiments.

[0070] (7) A process for producing a semiconductor device whichcomprises

[0071] a step forming an intermetal insulating film containing at leastsilicon atoms, oxygen atoms, and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and having a shrinkage in thefilm thickness direction at a time of oxidation of 14% or less,

[0072] a step of forming one or more trenches or holes in the intermetalinsulating film,

[0073] a step of depositing a metal film so as to fill the trenches orholes, and

[0074] a step of removing the metal film from portions other thaninsides of the trenches or holes by chemical-mechanical polishingprocess.

[0075] (8) A process mentioned in above (7), which further comprises astep of exposing the intermetal insulting film to plasma containingoxygen under a pressure of 50 mTorr or less.

[0076] (9) A process for producing a semiconductor device whichcomprises

[0077] a step forming an intermetal insulating film containing at leastsilicon atoms, oxygen atoms, and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and having a shrinkage in thefilm thickness direction at a time of oxidation of 10% or less,

[0078] a step of forming one or more trenches or holes in the intermetalinsulating film,

[0079] a step of depositing a metal film so as to fill the trenches orholes, and

[0080] a step of removing the metal film from portions other thaninsides of the trenches or holes by chemical-mechanical polishingprocess.

[0081] (10) A process mentioned in above (9), which further comprises astep of exposing the intermetal insulting film to plasma containingoxygen under a pressure of 50 mTorr or less

[0082] (11) A process for producing a semiconductor device whichcomprises

[0083] a step of forming a first wire by dry etching of a metal film,

[0084] a step of forming a first insulating film containing at leastsilicon atoms, oxygen atoms, and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and having a shrinkage in thefilm thickness direction at a time of oxidation of 14% or less,

[0085] a step of forming a coated insulating film,

[0086] a step of forming a second insulating film containing at leastsilicon atoms, oxygen atoms and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and having a shrinkage in thefilm thickness direction at a time of oxidation of 14% or less,

[0087] a step of forming holes in a stack comprising the firstinsulating film, the coated insulating film and the second insulatingfilm so as to expose a surface of the first wire,

[0088] a step of filling a metal film in the holes, and

[0089] a step of removing the metal film from outside of the holes.

[0090] (12) A process mentioned in above (11), which further comprises astep of removing a resist used for forming the holes by a plasmatreatment containing at least oxygen under a pressure of 50 mTorr orless between the step of forming the holes and the step of filling themetal film in the holes.

[0091] (13) A process for producing a semiconductor device whichcomprises

[0092] a step of forming a first wire by dry etching of a metal film,

[0093] a step of forming a first insulating film containing at leastsilicon atoms, oxygen atoms, and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and having a shrinkage in thefilm thickness direction at a time of oxidation of 10% or less,

[0094] a step of forming a coated insulating film,

[0095] a step of forming a second insulating film containing at leastsilicon atoms, oxygen atoms and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and having a shrinkage in thefilm thickness direction at a time of oxidation of 10% or less,

[0096] a step of forming holes in a stack comprising the firstinsulating film, the coated insulating film and the second insulatingfilm so as to expose a surface of the first wire,

[0097] a step of filling a metal film in the holes, and

[0098] a step of removing the metal film from outside of the holes.

[0099] (14) A process mentioned in above (13), which further comprises astep of removing a resist used for forming the holes by a plasmatreatment containing at least oxygen under a pressure of 50 mtorr orless between the step of forming the holes and the step of filling themetal film in the holes.

[0100] The present invention is illustrated by way of the followingExamples, but needless to say, not limited thereto.

EXAMPLE 1

[0101] Using a plasma CVD apparatus having a parallel plate type chamberas shown in FIG. 9, an organic siloxane film with 200 nm thick wasformed on a Si substrate. Conditions for film formation were as follows:Liquid source: monomethylethoxysilane [CH₃Si(OC₂H₅)₃] Bubblertemperature: 37° C. Carrier He flow rate: 200 sccm N₂ flow rate: 200sccm Pressure: 5 Torr Substrate temperature: 375° C. RF power: 500 WElectrode distance: 180 mils

[0102] The formed film had a dielectric constant of 3.2, a dielectricbreakdown voltage of 5 MV/cm. Measurement by a Fourier-transforminfrared absorption spectrophotometry (FTIR) of the film revealed bondsof Si—O—Si, Si—CH₃, as well as Si—C—Si and Si—H obtained bydecomposition of Si—CH₃ (FIG. 10). Number ratios of atoms in the film byan Auger analysis revealed C/Si being 1.6/1 and O/Si being 1.8/1. Thenitrogen used as a reaction gas was also included in the film in theratio of N/Si of about 0.1.

[0103] The resulting film was subjected to a high-pressure oxygen-plasmatreatment using a barrel type ashing equipment. The treating conditionswere an oxygen flow rate of 200 sccm, a pressure of 1 Torr, a RF powerof 300 W, a time of 15 minutes.

[0104] The organic components in the film were decomposed to give anoxidized film. A change in film thickness measured by ellipsometry wasless than 5%.

[0105] Separately, the same film as mentioned above was formed andsubjected to an oxygen plasma treatment using a reactive ion etchingapparatus employing low pressure conditions used for removing a resistfrom an organic siloxane film. The treating conditions were an oxygenflow rate of 50 sccm, a pressure of 10 mTorr, a RF power of 700 W and atime of 1 minute.

[0106] The organic components in the film were hardly decomposed and thesurface of about 10 nm thick was oxidized. On this film, titaniumnitride of 50 nm thick and copper of 500 nm thick were formed. Then, thesurface was crosswisely scratched using a diamond needle and subjectedto an adhesion test using an adhesive tape. No delamination of titaniumnitride and copper was observed.

[0107] When He was used as an inert gas in place of the nitrogen, theresults of adhesion test were not changed, but the carbon content in thefilm increased. This seems to be a large amount of unnecessary carboncomponents not contributing to bonding of the film.

[0108] When oxygen was used in place of the nitrogen, the bonds ofSi—CH₃, Si—C—Si and Si—H were reduced. The film had a dielectricconstant of 4 or more failing to obtain a low dielectric constant.

[0109] In order to reduce unnecessary carbon components and to obtainthe above-mentioned properties, the use of a reducing gas such asnitrogen, hydrogen, ammonia, or a mixture thereof was most suitable.

[0110] Even if monomethyltrimethoxysilane [CH₃Si(OCH₃)₃] was used as aliquid source, the same results were obtained by lowering the bubblertemperature so as to obtain the same pressure as mentioned above.

Example 2

[0111] Films were formed by changing the pressure to study film qualitydependency. The film forming conditions were the same as those ofExample 1 except for the pressure. Since the total gas flow rate wasconstant, the pressure was proportional to the residence time.

[0112]FIG. 11 shows the pressure dependency of FTIR spectra. Theordinate axis is normalized by the peak value of the Si—O—Si bond at thewavenumber of 1030 kayser. In the graph, the Si—CH₃ bond at 1280 kayserand the Si—H bond at 885 kayser are shown. At near 790 kayser, aplurality of Si—C—Si bonds with the same size are present andoverlapped, resulting in failing to separate individually. Thus, thewavenumber showing the maximum peak and the maximum peak value between750 to 850 kaysers are shown for convenience. Black circles show a casewhere the 790 kayser having the Si—C—Si bond is the maximum and whitecircles show a case wherein the 770 kaysers having the Si—CH₃ bond isthe maximum.

[0113] When the pressure is high, the Si—CH₃ bond is large and the Si—Hbond is small. Between 750-850 kaysers, the wavenumber showing themaximum peak is 770 kayser. This means that a reaction for producingSi—C—Si and Si—H by decomposition of Si—CH₃ does not take place so much,resulting in retaining Si—CH₃ in a large amount. When the pressurebecomes lower and lower, the Si—CH₃ bond decreases and the Si—H bondincreases. The wavenumber showing the maximum peak between 750 to 850kaysers is 790 kayser, which corresponds to the Si—C—Si bond. When thepressure becomes lower, the peak of the Si—C—Si bond increases. From theabove results, it becomes clear that in order to produce Si—C—Si bydecomposition of Si—CH₃, the residence time should be shortened.

[0114]FIG. 12 shows the shrinkage of film thickness during high-pressureoxygen plasma treatment using a barrel type asher (ashing equipment).The conditions for the oxygen plasma treatment are the same as those inExample 1. FIG. 12 shows that the shrinkage of film thickness issmaller, when the pressure is lower and the residence time is longer.

[0115] Further, in order to conduct the adhesion test, an insulatingfilm of 200 nm thick was formed on a Si substrate, followed by lowpressure oxygen plasma treatment to form titanium nitride and copper.The conditions for these treatment were the same as those of Example 1.Then, CMP was conducted to observe the presence of delamination.

[0116] No delamination was observed at all under the pressure of 9 Torror less. When the pressure became to 13 and 15 Torr, fine delaminationwith a diameter of 0.1 mm or less was observed in several portions. Whenthe pressure became larger than that, further larger delaminations wereobserved. This means that in order to obtain good adhesiveness, theshrinkage of film thickness at the time of oxidation is made preferably14% or less, more preferably 10% or less. Further, in order to producethe film by the above-mentioned method, it is preferable to make the(pressure in the reactor)·(volume in the reactor)/(total gas flow rate)500 Torr·sec or less, more preferably 280 Torr·sec or less.

Example 3

[0117] Films were produced by changing the liquid source materials tostudy material dependency of the film quality. When two liquid sourceswere used, two bubblers which controled the bubbler temperature and theHe flow rate independently. By this, the total flow rate of the carrierHe was adjusted to be 200 sccm and the vapor amount of the liquid sourcein the carrier was controlled to be the same as that in Example 1.Forming conditions other than those mentioned above were the same asthose of Example 1.

[0118] The vapor amount of liquid source in 200 sccm of the carrier gasis shown below (relative values taking the vapor amount of Example 1 as1). (a) Si(OC₂H₅)₄ 1 (b) Si(OC₂H₅)₄ 0.25 CH₃Si(OC₂H₅)₃ 0.75 (c)CH₃Si(OC₂H₅)₃ 1 (d) CH₃Si(OC₂H₅)₃ 0.5 (CH₃)₂Si(OC₂H₅)₂ 0.5 (e)(CH₃)₂Si(OC₂H₅)₂ 1

[0119] When the above-mentioned formulae are represented by the formula:(CH₃)_(n)Si(OC₂H₅)_(4−n), n in (a) to (e) corresponds to (a) n=0, (b)n=0.5, (c) n=1, (d) n=1.5 and (e) n=2.

[0120]FIG. 13 is a graph showing relations between the dielectricconstant and O/Si ratio, C/Si ratio, and n. As is clear from FIG. 13, inorder to realize the dielectric constant of 3.5 or less, the O/Si ratioof 1.5 or more and the C/Si ratio of 1 to 2, n is 0.75 or more and 1.5or less.

[0121] Further, the above films (n=0.75-1.5) were subjected to thehigh-pressure oxygen plasma treatment using a barrel type asher. Thetreatment conditions were the same as those of Example 1. The change offilm thickness measured by ellipsometry was less than 10% in each case.

Example 4

[0122] Using the film of Example 1, a multilevel wiring in asemiconductor device was prepared. Copper wiring was formed by using asingle damascene process.

[0123] On a semiconductor substrate 0 having a gate electrode oftransistor 1 and a contact electrode 2 thereon, the film 4 of Example 1was formed in 300 nm thick, and a trench pattern 16 corresponding to afirst level wiring was formed (FIG. 14). After removing a resist 6 usinga low pressure oxygen reactive ion etching at a pressure of 10 mTorr,titanium nitride 17 in 500 nm thick and copper 18 in 100 nm thick wereformed by sputtering, followed by filling of copper in the pattern usingelectroplating (FIG. 15). Then, the copper and titanium nitride outsidethe pattern were removed by CMP to give the first level wiring (FIG.16).

[0124] Then, a silicon nitride film 5 in 50 nm thick and the film 4 ofExample 1 in 400 nm thick were formed, followed by formation of holepattern 26 corresponding to via connection (FIG. 17). At this time, theetching was stopped on the silicon nitride so as not to expose thecopper. After removing the resist by a low pressure oxygen reactive ionetching at a pressure of 10 mTorr, the silicon nitride retaining at thebottom of the hole was subjected to etching to expose the copper. Then,after forming titanium nitride 17 in 50 nm thick and copper 18 in 100 nmthick by sputtering, copper was filled in the pattern by electroplating(FIG. 18). Further, the copper and titanium nitride outside pattern wereremoved by CMP to give via connection (FIG. 19).

[0125] Then, a silicon nitride film 5 in 50 nm thick and the film 4 ofExample 1 in 250 nm thick were formed, followed by formation of a trenchpattern 36 corresponding to a second level wiring (FIG. 20). The etchingwas conducted in the same manner as mentioned above. After removing theresist using a low pressure oxygen reactive ion etching at a pressure of10 mTorr, the silicon nitride retaining at the bottom of the trench wasetched to expose the copper. Then, titanium nitride 17 in 50 nm thickand copper 18 in 100 nm thick were formed by sputtering, followed byfilling of copper in the pattern using electroplating (FIG. 21).Further, the copper and titanium nitride outside the pattern wereremoved by CMP to form the second level wiring (FIG. 22).

[0126] Then, repeating the same treatments as shown in FIGS. 17 to 22, athird level wiring was formed (FIG. 23).

[0127] In all the steps mentioned above, there arose no problem ofdelamination.

[0128] For comparison, a sample using a silicon oxide protective film of100 nm thick was also prepared. The film thickness of the film ofExample 1 was reduced in 100 nm in all the level wiring so as to makethe wiring height and the via height the same. When an effectivedielectric constant in the second level wiring and that between upperand lower level wiring was measured, the effective dielectric constantwas about 10% lower than the case of not using the silicon oxideprotective film.

Example 5

[0129] Multilevel wiring of a semiconductor device was prepared by usingthe film of Example 1 and an organic polymer film (a trade name SiLK,mfd. by Dow Chemical Co., dielectric constant 2.7). The copper wiringwas formed by a single damascene process.

[0130] After the step shown in FIG. 16, a silicon nitride film 5 in 50nm thick and an organic polymer film 7 in 300 nm thick, and the film 4of Example 1 in 100 nm thick were formed, followed by formation of ahole pattern 26 corresponding to the via connection (FIG. 24). At thistime, the film of Example 1 was etched first, followed by simultaneousetching of the organic polymer film using this as a hard mask. Thesimultaneous etching was conducted by using a mixed gas of oxygen andnitrogen and low pressure reactive ion etching. Then, the siliconnitride retaining at the bottom of hole was etched to expose the copper.Then, titanium nitride 17 in 50 nm thick and copper 18 in 100 nm thickwere formed by sputtering, followed by filling of copper in the patternby electroplating (FIG. 25). Further, after removing the copper andtitanium nitride outside the pattern by CMP, via connection was formed(FIG. 26). At this time, no problem of delamination arose.

[0131] Then, a silicon nitride film 5 in 50 nm thick, an organic polymerfilm 7 in 150 nm thick, and the film 4 of Example 1 in 100 nm thick wereformed, followed by formation of a trench pattern 36 corresponding tothe second level wiring (FIG. 27). The etching was conducted in the samemanner as mentioned above. Then, the silicon nitride retaining at thebottom of trench was etched to expose the copper. Then, titanium nitride17 in 50 nm and copper 18 in 100 nm thick were formed by sputtering, andthe pattern was filled with copper using electroplating (FIG. 28).Further, the copper and titanium nitride outside the pattern wereremoved by CMP to form the second level wiring (FIG. 29).

[0132] Then, repeating the same treatments as shown in FIGS. 24 to 29, athird level wiring was formed (FIG. 30).

[0133] In all the steps mentioned above, no problem caused bydelamination took place.

[0134] For comparison, a sample using a silicon oxide protective film of100 nm thick was also prepared. The film thickness of the film ofExample 1 was reduced in 100 nm in all the level wiring so as to makethe wiring height and the via connection height the same. When aneffective dielectric constant in the second level wiring and thatbetween upper and lower level wiring was measured, the effectivedielectric constant was about 10% lower than the case of not using thesilicon oxide protective film.

Example 6

[0135] Multilevel wiring of a semiconductor device was prepared by usingthe film of Example 1. The copper wiring was formed by a dual damasceneprocess having less steps compared with a single damascene process.

[0136] After the step shown in FIG. 16, a silicon nitride film 5 in 50nm thick and the film 4 of Example 1 in 700 nm thick were formed,followed by formation of a hole pattern 26 corresponding to the viaconnection (FIG. 31). At this time, the etching was stopped on thesilicon nitride so as not to expose the copper. After removing theresist using a low pressure oxygen reactive ion etching at a pressure of10 mTorr, a trench pattern 36 corresponding to a second level wiring wasformed (FIG. 32). After removing the resist 6 using a low pressureoxygen reactive ion etching at a pressure of 10 mTorr, the siliconnitride retaining at the bottom of hole was etched to expose the copper.Then, titanium nitride 17 in 50 nm thick and copper 18 in 100 nm thickwere formed by sputtering, followed by filling of copper in the patternby electroplating (FIG. 33). Further, after removing the copper andtitanium nitride outside the pattern by CMP, via connection and a secondlevel wiring were formed (FIG. 34).

[0137] Then, repeating the same treatments as shown in FIGS. 31 to 34, athird level wiring was formed (FIG. 35).

[0138] In all the steps mentioned above, no problem caused bydelamination took place.

Example 7

[0139] Using the film of Example 1, a multilevel wiring in asemiconductor device was prepared. Aluminum alloy wiring was formed by adry etching process.

[0140] First, on a semiconductor substrate 0 have a gate electrode oftransistor 1 and a contact electrode 2 thereon, titanium nitride 17 in50 nm thick, aluminum alloy 19 in 300 nm thick and titanium nitride 17in 50 nm thick were formed. Then, a first level wiring was formed byphotolithography and dry etching, followed by removal of the resist(FIG. 36).

[0141] After forming the film of Example 1 in 50 nm thick, a trench wasfilled with an organic spin-on glass (a trade name, HSG-R7, mfd. byHitachi Chemical Company, Ltd.) in 250 nm thick, followed by formationof the film of Example 1 in 1000 nm thick. After planarizing the surfaceby CMP, a hole pattern 26 corresponding to a via connection was formed(FIG. 37). After removing the resist 6 using a low pressure oxygenreactive ion etching at a pressure of 10 mTorr, titanium nitride 17 in50 nm thick was formed by sputtering and tungsten 20 in 300 nm thick wasformed by CVD method to fill the hole (FIG. 38). Further, the tungstenand titanium nitride outside the pattern were removed by CMP to form viaconnection (FIG. 39). Then, titanium nitride in 50 nm thick, aluminumalloy in 300 nm thick and titanium nitride in 50 nm thick were formed. Asecond level wiring was formed by photolithography and dry etching,followed by removal of resist (FIG. 40). At this time, a low pressureoxygen reactive ion etching at a pressure of 10 mTorr was used forremoval of the resist.

[0142] Repeating the same treatments as shown in FIGS. 37 to 40, a thirdlevel wiring was formed (FIG. 41). In FIG. 41, numerals 27, 37, 47 and57 denote a barrier metal, numerals 29 and 48 denote tungsten, andnumerals 38 and 58 denote aluminum alloy, respectively.

[0143] In the all steps mentioned above, no problems caused bydelamination took place.

[0144] For comparison, a sample using a silicon oxide film in place ofthe film of Example 1 was also prepared. When an effective dielectricconstant in the second level wiring and that between upper and lowerlevel wiring was measured, the effective dielectric constant was about10% between neighboring wiring and 20% between upper and lower levelslower than the case of not using the silicon oxide film.

[0145] When the low dielectric insulating film forming holes or trenchpatterns therein is subjected to formation of a metal film directly,followed by polishing, the metal film is not delaminated. This isbecause the shrinkage on the surface of the insulating film caused byremoval of resist after pattern formation is small.

[0146] Therefore, when a conventional stacked film comprising a lowdielectric constant film and a silicon oxide protective film is replacedby the low dielectric constant film of the present invention, themanufacturing steps are reduced, and an increase of effective dielectricconstant due to the silicon oxide film can be prevented. Further, whenthe low dielectric constant film of the present invention is used as aprotective film for another low dielectric constant insulting film, anincrease of effective dielectric constant due to the silicon oxide filmcan also be reduced.

What is claimed is:
 1. A semiconductor device including one or moreintermetal insulating films, each intermetal insulating film containingat least silicon atoms, oxygen atoms, and carbon atoms with the numberratio of oxygen atom to silicon atom being 1.5 or more and the numberratio of carbon atom to silicon atom being 1 to 2, and having ashrinkage in the film thickness direction at a time of oxidation of 14%or less.
 2. A semiconductor device according to claim 1, wherein theshrinkage in the film thickness direction at the time of oxidation is10% or less.
 3. A semiconductor device according to claim 1, wherein theintermetal insulating film has a relative dielectric constant of 3.5 orless.
 4. A semiconductor device according to claim 1, wherein theintermetal insulating film has all of Si—CH₃ bond, Si—O—Si bond andSi—C—Si bond.
 5. A process for producing a semiconductor devicecomprising a step of forming an intermetal insulating film using a mixedgas comprising a vapor of monomethyltriethoxysilane represented by theformula: RSi(OR′)₃, wherein R is a methyl group and R′ is an ethylgroup, and a non-oxidizing gas by means of a plasma chemical vapordeposition method, and a step of forming wires.
 6. A process accordingto claim 5, wherein the non-oxidizing gas is a nitrogen gas, a hydrogengas, an ammonia gas, a helium gas, an argon gas or a mixture thereof. 7.A process according to claim 5, wherein the non-oxidizing gas is amixture of a nitrogen gas and an inert gas.
 8. A process according toclaim 5, wherein the intermetal insulating film is formed under acondition of (pressure in a reactor)·(volume of the reactor)/(total gasflow rate) of 500 Torr·sec or less.
 9. A process according to claim 8,wherein the intermetal insulating film is formed under a condition of(pressure in a reactor)·(volume of the reactor)/(total gas flow rate) of280 Torr·sec or less.
 10. A process for producing a semiconductor devicewhich comprises a step of forming an intermetal insulating film using amixed gas comprising a vapor of methylethoxysilane represented by theformula: R_(n)Si(OR′)_(4−n), wherein R is a methyl group, R′ is an ethylgroup, and n is 0 to 2, said vapor being mixed so as to make R 0.75 to1.5 per silicon, and a non-oxidizing gas by means of a plasma chemicalvapor deposition method, and a step of forming wires.
 11. A processaccording to claim 10, wherein the non-oxidizing gas is a nitrogen gas,a hydrogen gas, an ammonia gas, a helium gas, an argon gas or a mixturethereof.
 12. A process according to claim 10, wherein the non-oxidizinggas is a mixture of a nitrogen gas and an inert gas.
 13. A processaccording to claim 10, wherein the intermetal insulating film is formedunder a condition of (pressure in a reactor)·(volume of thereactor)/(total gas flow rate) of 500 Torr·sec or less.
 14. A processaccording to claim 13, wherein the intermetal insulating film is formedunder a condition of (pressure in a reactor)·(volume of thereactor)/(total gas flow rate) of 280 Torr·sec or less.
 15. A processfor producing a semiconductor device which comprises a step of formingan intermetal insulating film using a mixed gas comprising (a) a vaporof monomethyltriethoxysilane represented by the formula: RSi(OR′)₃,wherein R and R′ are each methyl group, or (b) a vapor ofmethylmethoxysilane represented by the formula: R_(n)Si(OR′)_(4−n),wherein R and R′ are each methyl group, and n is 0 to 2, said vaporbeing mixed so as to make R 0.75 to 1.5 per silicon, and a non-oxidizinggas by means of a plasma chemical vapor deposition method, and a step offorming wires.
 16. A process according to claim 15, wherein thenon-oxidizing gas is a nitrogen gas, a hydrogen gas, an ammonia gas, ahelium gas, an argon gas or a mixture thereof.
 17. A process accordingto claim 15, wherein the non-oxidizing gas is a mixture of a nitrogengas and an inert gas.
 18. A process according to claim 15, wherein theintermetal insulating film is formed under a condition of (pressure in areactor)·(volume of the reactor)/(total gas flow rate) of 500 Torr·secor less.
 19. A process according to claim 18, wherein the intermetalinsulating film is formed under a condition of (pressure in areactor)·(volume of the reactor)/(total gas flow rate) of 280 Torr·secor less.
 20. A process for producing a semiconductor device whichcomprises a step forming an intermetal insulating film containing atleast silicon atoms, oxygen atoms, and carbon atoms with the numberratio of oxygen atom to silicon atom being 1.5 or more and the numberratio of carbon atom to silicon atom being 1 to 2, and having ashrinkage in the film thickness direction at a time of oxidation of 14%or less, a step of forming one or more trenches or holes in theintermetal insulating film, a step of depositing a metal film so as tofill the trenches or holes, and a step of removing the metal film fromportions other than insides of the trenches or holes bychemical-mechanical polishing process.
 21. A process according to claim20, which further comprises a step of exposing the intermetal insultingfilm to plasma containing oxygen under a pressure of 50 mTorr or less.22. A process for producing a semiconductor device which comprises astep forming an intermetal insulating film containing at least siliconatoms, oxygen atoms, and carbon atoms with the number ratio of oxygenatom to silicon atom being 1.5 or more and the number ratio of carbonatom to silicon atom being 1 to 2, and having a shrinkage in the filmthickness direction at a time of oxidation of 10% or less, a step offorming one or more trenches or holes in the intermetal insulating film,a step of depositing a metal film so as to fill the trenches or holes,and a step of removing the metal film from portions other than insidesof the trenches or holes by chemical-mechanical polishing process.
 23. Aprocess according to claim 22, which further comprises a step ofexposing the intermetal insulting film to plasma containing oxygen undera pressure of 50 mTorr or less.
 24. A process for producing asemiconductor device which comprises a step of forming a first wire bydry etching of a metal film, a step of forming a first insulating filmcontaining at least silicon atoms, oxygen atoms, and carbon atoms withthe number ratio of oxygen atom to silicon atom being 1.5 or more andthe number ratio of carbon atom to silicon atom being 1 to 2, and havinga shrinkage in the film thickness direction at a time of oxidation of14% or less, a step of forming a coated insulating film, a step offorming a second insulating film containing at least silicon atoms,oxygen atoms and carbon atoms with the number ratio of oxygen atom tosilicon atom being 1.5 or more and the number ratio of carbon atom tosilicon atom being 1 to 2, and having a shrinkage in the film thicknessdirection at a time of oxidation of 14% or less, a step of forming holesin a stack comprising the first insulating film, the coated insulatingfilm and the second insulating film so as to expose a surface of thefirst wire, a step of filling a metal film in the holes, and a step ofremoving the metal film from outside of the holes.
 25. A processaccording to claim 24, which further comprises a step of removing aresist used for forming the holes by a plasma treatment containing atleast oxygen under a pressure of 50 mTorr or less between the step offorming the holes and the step of filling the metal film in the holes.26. A process for producing a semiconductor device which comprises astep of forming a first wire by dry etching of a metal film, a step offorming a first insulating film containing at least silicon atoms,oxygen atoms, and carbon atoms with the number ratio of oxygen atom tosilicon atom being 1.5 or more and the number ratio of carbon atom tosilicon atom being 1 to 2, and having a shrinkage in the film thicknessdirection at a time of oxidation of 10% or less, a step of forming acoated insulating film, a step of forming a second insulating filmcontaining at least silicon atoms, oxygen atoms and carbon atoms withthe number ratio of oxygen atom to silicon atom being 1.5 or more andthe number ratio of carbon atom to silicon atom being 1 to 2, and havinga shrinkage in the film thickness direction at a time of oxidation of10% or less, a step of forming holes in a stack comprising the firstinsulating film, the coated insulating film and the second insulatingfilm so as to expose a surface of the first wire, a step of filling ametal film in the holes, and a step of removing the metal film fromoutside of the holes.
 27. A process according to claim 26, which furthercomprises a step of removing a resist used for forming the holes by aplasma treatment containing at least oxygen under a pressure of 50 mTorror less between the step of forming the holes and the step of fillingthe metal film in the holes.
 28. A semiconductor device including one ormore wiring layers, each layer having a plurality of inlaid wires andintermetal insulating films between individual inlaid wires, saidintermetal insulating film being a single layer film of a low dielectricconstant film having a dielectric constant lower than that of a siliconoxide film.
 29. A semiconductor device according to claim 28, whereinthe low dielectric constant film contains at least silicon atoms, oxygenatoms and carbon atoms with the number ratio of oxygen atom to siliconatom being 1.5 or more and the number ratio of carbon atom to siliconatom being 1 to 2, and has a shrinkage in the film thickness directionat a time of oxidation of 14% or less.
 30. A semiconductor deviceaccording to claim 28, wherein the low dielectric constant film containsat least silicon atoms, oxygen atoms and carbon atoms with the numberratio of oxygen atom to silicon atom being 1.5 or more and the numberratio of carbon atom to silicon atom being 1 to 2, and has a shrinkagein the film thickness direction at a time of oxidation of 10% or less.31. A semiconductor device including one or more wiring layers, eachlayer having a plurality of inlaid wires and intermetal insulating filmsbetween individual inlaid wires, said intermetal insulating film being astack of a plurality of insulating films, the uppermost insulating filmbeing a low dielectric constant film having a dielectric constant lowerthan that of a silicon oxide film.
 32. A semiconductor device accordingto claim 31, wherein the low dielectric constant film contains at leastsilicon atoms, oxygen atoms and carbon atoms with the number ratio ofoxygen atom to silicon atom being 1.5 or more and the number ratio ofcarbon atom to silicon atom being 1 to 2, and has a shrinkage in thefilm thickness direction at a time of oxidation of 14% or less.
 33. Asemiconductor device according to claim 31, wherein the low dielectricconstant film contains at least silicon atoms, oxygen atoms and carbonatoms with the number ratio of oxygen atom to silicon atom being 1.5 ormore and the number ratio of carbon atom to silicon atom being 1 to 2,and has a shrinkage in the film thickness direction at a time ofoxidation of 10% or less.